I used Crayola Air-Drying clay to make the horns, wrapped around a foil base, and glued onto a plastic headband which is attached to the wig by string (so that I can reuse the wig if I wish)
I used Snazaroo grey facepaint, it's very good and at an excellent price. It doesn't smear very bad, only needs touchups every few hours. I had it on the palms of my hands and still didn't have many problems, definitely suggested.

I am working on making his sickle, out of thick posterboard and a 1 1/2'' thick dowel rod.